1. Field of the Invention
The present invention relates to an apparatus for performing an operation on a circuit substrate such as a printed-wiring board, and particularly to the art of improving the safety of maintenance of the apparatus.
2. Discussion of Related Art
There are known various sorts of operation-on-circuit-substrate performing apparatuses such as a circuit-substrate machining apparatus that machines a circuit substrate, e.g., makes a hole in a circuit substrate; a screen printing apparatus that prints a high-viscosity fluid such as cream solder on a circuit substrate; a high-viscosity-fluid applying apparatus that applies a high-viscosity fluid, such as an adhesive, in the form of spots on a circuit substrate; an electric-component mounting apparatus that mounts an electric component (e.g., an electronic component) on a circuit substrate; and a circuit-substrate inspecting apparatus that inspects a circuit substrate before or after an electric component is mounted on the circuit substrate. Usually, an operation-on-circuit-substrate performing apparatus is provided with a safety cover for preventing a portion of a living person from entering an operation space or being injured because of the entrance.
However, the maintenance of the operation-on-circuit-substrate performing apparatus includes some operations each of which needs to operate at least one of a plurality of operating devices of the apparatus in a state in which the safety cover of the apparatus is opened. To this end, it is practiced to provide the apparatus with a bypass-key switch. More specifically described, when a special key called “bypass key” is inserted in a keyhole, a safety-cover switch is bypassed to close an electric circuit, so that at least one of the operating devices is made operable. This bypass key can be used by a very limited person or persons only, in a very limited case or cases only, and thus the maintenance of the apparatus is performed very carefully. Nonetheless, it is difficult to completely prevent all persons from being injured.